Inverter System

This application claims priority to Japanese Patent Application No. 2025-029501 filed on February 26, 2025. The disclosure of the above-identified application, including the specification, drawings, and claims, is incorporated by reference herein in its entirety.

The present disclosure relates to an inverter system that is mounted in a vehicle.

As an inverter that is mounted in a vehicle, a three-level inverter that converts direct current power output by a battery into three-phase alternating current power is known (for example, refer to Japanese Unexamined Patent Application Publication No. 2024-101332 (JP 2024-101332 A)).

An object of the present disclosure is to provide an inverter system capable of improving limp home performance of a vehicle.

A first aspect of the present disclosure is an inverter system including: an inverter configured to convert a direct current voltage into voltages of three different levels and output three-phase alternating current power; and a control device configured to control the inverter, in which: the inverter includes a high-potential wiring line that is connected to a positive electrode of a power supply, a low-potential wiring line that is connected to a negative electrode of the power supply, at least one neutral point having a potential between a potential of the high-potential wiring line and a potential of the low-potential wiring line, a first capacitor connected between the high-potential wiring line and the neutral point, a second capacitor connected between the neutral point and the low-potential wiring line, three upper arm elements corresponding to respective three phases, three lower arm elements corresponding to the respective three phases, three middle elements corresponding to the respective three phases, and a first switch element provided between a connection position of the first capacitor and a connection position of the three upper arm elements in the high-potential wiring line, the first switch element being configured to switch conduction and interruption in the high-potential wiring line; and the control device is configured to execute determining whether at least one of the three upper arm elements fails, and controlling, in accordance with determining that at least one of the three upper arm elements fails, the first switch element such that there is an interruption in the high-potential wiring line.

A second aspect of the present disclosure is an inverter system including: an inverter configured to convert a direct current voltage into voltages of three different levels and output three-phase alternating current power; and a control device configured to control the inverter, in which: the inverter includes a high-potential wiring line that is connected to a positive electrode of a power supply, a low-potential wiring line that is connected to a negative electrode of the power supply, at least one neutral point having a potential between a potential of the high-potential wiring line and a potential of the low-potential wiring line, a first capacitor connected between the high-potential wiring line and the neutral point, a second capacitor connected between the neutral point and the low-potential wiring line, three upper arm elements corresponding to respective three phases, three lower arm elements corresponding to the respective three phases, three middle elements corresponding to the respective three phases, and a second switch element provided between a connection position of the second capacitor and a connection position of the three lower arm elements in the low-potential wiring line, the second switch element being configured to switch conduction and interruption in the low-potential wiring line; and the control device is configured to execute determining whether at least one of the three lower arm elements fails, and controlling, in accordance with determining that at least one of the three lower arm elements fails, the second switch element such that there is an interruption in the low-potential wiring line.

According to the present disclosure, it is possible to provide an inverter system capable of improving limp home performance of a vehicle.

A three-phase three-level inverter is known as an inverter mounted in a vehicle such as a BEV, an HEV, or a PHEV. In such an inverter, in a case where an upper arm element or a lower arm element is short-circuited, a middle element is also short-circuited in a case where the middle element is turned on. As a result, the inverter cannot perform an operation of using the middle element in addition to an operation of using the failed upper arm element or lower arm element. As a result, there is a problem that limp home performance of the vehicle is deteriorated. The present disclosure solves the problem.

According to a first aspect of the present disclosure, there is provided an inverter system including: an inverter that converts a direct current voltage into voltages of three different levels and outputs three-phase alternating current power; and a control device that controls the inverter. In the first aspect of the present disclosure, the inverter includes a first switching element. The first switching element is provided between a connection position of a first capacitor and a connection position of three upper arm elements in a high-potential wiring line of the inverter and is configured to switch conduction and interruption of the high-potential wiring line. In addition, in the first aspect of the present disclosure, the control device is configured to execute determining whether at least one of the three upper arm elements fails. In addition, in the first aspect of the present disclosure, the control device is configured to execute controlling the first switching element to interrupt the high-potential wiring line in accordance with the determination that at least one of the three upper arm elements fails.

According to the first aspect of the present disclosure, in a case where at least one of the three upper arm elements is short-circuited, the first switching element interrupts the high-potential wiring line between the first capacitor and the three upper arm elements. Therefore, even in a case where the middle element is turned on, it is possible to prevent the middle element from being short-circuited. As a result, the inverter can also perform an operation of using the middle element in addition to an operation of using the lower arm element. Therefore, it is possible to improve the limp home performance of the vehicle.

In addition, according to a second aspect of the present disclosure, there is provided an inverter system including: an inverter that converts a direct current voltage into voltages of three different levels and outputs three-phase alternating current power; and a control device that controls the inverter. In the second aspect of the present disclosure, the inverter includes a second switching element. The second switching element is provided between a connection position of a second capacitor and a connection position of three lower arm elements in a low-potential wiring line of the inverter and is configured to switch conduction and interruption of the low-potential wiring line. In addition, in the second aspect of the present disclosure, the control device is configured to execute determining whether at least one of the three lower arm elements fails. In addition, in the second aspect of the present disclosure, the control device is configured to execute controlling the second switching element to interrupt the low-potential wiring line in accordance with the determination that at least one of the three lower arm elements fails.

According to the second aspect of the present disclosure, in a case where at least one of the three lower arm elements is short-circuited, the second switching element interrupts the low-potential wiring line between the second capacitor and the three lower arm elements. Therefore, even in a case where the middle element is turned on, it is possible to prevent the middle element from being short-circuited. As a result, the inverter 11 can also perform an operation of using the middle element in addition to an operation of using the upper arm element. Therefore, it is possible to improve the limp home performance of the vehicle.

Hereinafter, specific embodiments of the present disclosure will be described with reference to the drawings. Unless otherwise specified, the hardware configuration, module configuration, functional configuration, and the like described in each embodiment are not intended to limit the technical scope of the disclosure.

1 FIG. 1 1 1 1 1 10 11 12 13 h h In the present embodiment, an example of applying an inverter system according to the present disclosure to a vehicle will be described.is a diagram schematically showing an example of a schematic configuration of an inverter systemin the present embodiment. The inverter systemin the present embodiment is mounted in a vehicle V. The vehicle Vmay be a BEV, an HEV, or a PHEV. The inverter systemis configured to include a battery, an inverter, a motor, and an ECU.

10 10 10 12 1 11 10 12 10 12 12 1 1 13 11 1 h h h h The batteryis a secondary battery that outputs direct current power, and is an example of a "power supply" according to the present disclosure. In the example, the batterymay be a lithium ion battery. The batteryis not limited to the lithium ion battery, and may be a nickel hydrogen battery, a nickel cadmium battery, an all-solid state battery, or the like. The motoris a three-phase AC motor that functions as a prime mover of the vehicle V. The inverteris disposed between the batteryand the motor, converts direct current power output from the batteryinto three-phase alternating current power, and supplies the converted three-phase alternating current power to the motor. As a result, the motordrives a wheel of the vehicle V, and the vehicle Vtravels. The ECUis a computer that controls the inverterin accordance with a driving condition of the vehicle V.

2 FIG. 2 FIG. 11 11 11 1 1 1 116 117 1 10 1 10 116 1 1 117 1 1 116 117 1 w p w w w w p p w p is a diagram showing an example of a circuit configuration of the inverterin the present embodiment. The inverterin the present embodiment is a three-level T-type inverter. As shown in, the inverterincludes a high-potential wiring line H, a neutral point N, a low-potential wiring line L, a first capacitor, and a second capacitor. The high-potential wiring line His connected to a positive electrode of the battery(power supply). The low-potential wiring line Lis connected to a negative electrode of the battery. The first capacitoris connected between the high-potential wiring line Hand the neutral point N. The second capacitoris connected between the neutral point Nand the low-potential wiring line L. The first capacitorand the second capacitorare smoothing capacitors that stabilize a voltage of the neutral point Nand reduce a current ripple.

11 110 110 111 111 112 112 110 110 111 111 112 112 110 110 111 111 112 112 1100 a b a b a b a b a b a b a b a b a b In addition, the inverterin the present embodiment includes a first switching element, a second switching element, a third switching element, a fourth switching element, a fifth switching element, and a sixth switching element. In the example, the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching elementmay be configured to include an arm element having an IGBT and a free-wheeling diode connected parallel to the IGBT. In the following description, the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching elementmay be referred to as a "switching element".

110 110 1 1 110 1 110 1 110 110 121 12 110 110 a b w w a w b w a b a b The first switching elementand the second switching elementare connected in series between the high-potential wiring line Hand the low-potential wiring line L. In this case, a drain terminal of the first switching elementis connected to the high-potential wiring line H, and a source terminal of the second switching elementis connected to the low-potential wiring line L. In addition, a source terminal of the first switching elementand a drain terminal of the second switching elementare connected to a U-phase coilof the motor. The first switching elementand the second switching elementmay be referred to as a U-phase upper arm element and a U-phase lower arm element, respectively.

111 111 1 1 111 1 111 1 111 111 122 12 111 111 a b w w a w b w a b a b The third switching elementand the fourth switching elementare connected in series between the high-potential wiring line Hand the low-potential wiring line L. In this case, a drain terminal of the third switching elementis connected to the high-potential wiring line H, and a source terminal of the fourth switching elementis connected to the low-potential wiring line L. In addition, a source terminal of the third switching elementand a drain terminal of the fourth switching elementare connected to a V-phase coilof the motor. The third switching elementand the fourth switching elementmay be referred to as a V-phase upper arm element and a V-phase lower arm element, respectively.

112 112 1 1 112 1 112 1 112 112 123 12 112 112 a b w w a w b w a b a b The fifth switching elementand the sixth switching elementare connected in series between the high-potential wiring line Hand the low-potential wiring line L. In this case, a drain terminal of the fifth switching elementis connected to the high-potential wiring line H, and a source terminal of the sixth switching elementis connected to the low-potential wiring line L. In addition, a source terminal of the fifth switching elementand a drain terminal of the sixth switching elementare connected to a W-phase coilof the motor. The fifth switching elementand the sixth switching elementmay be referred to as a W-phase upper arm element and a W-phase lower arm element, respectively.

110 111 112 110 111 112 a a a b b b The first switching element, the third switching element, and the fifth switching elementin the present embodiment are examples of an "upper arm element" according to the present disclosure. In addition, the second switching element, the fourth switching element, and the sixth switching elementin the present embodiment are examples of a "lower arm element" according to the present disclosure.

11 113 114 115 113 114 115 1100 In addition, the inverterin the present embodiment includes a first middle element portion, a second middle element portion, and a third middle element portion. Each of the first middle element portion, the second middle element portion, and the third middle element portionis configured to include two switching elements. Each of the two switching elements may be configured in the same manner as the switching element.

113 113 113 113 1 113 113 113 110 110 113 121 12 113 a b a p a b b a b b The first middle element portionincludes a first U-phase middle elementand a second U-phase middle elementas the two switching elements. A drain terminal of the first U-phase middle elementis connected to the neutral point N. A source terminal of the first U-phase middle elementis connected to a source terminal of the second U-phase middle element. A drain terminal of the second U-phase middle elementis connected to the source terminal of the first switching elementand the drain terminal of the second switching element. In other words, the drain terminal of the second U-phase middle elementis connected to the U-phase coilof the motor. The first middle element portionmay be referred to as a U-phase middle element.

114 114 114 114 1 114 114 114 110 111 114 122 12 114 a b a p a b b b a b The second middle element portionincludes a first V-phase middle elementand a second V-phase middle elementas the two switching elements. A drain terminal of the first V-phase middle elementis connected to the neutral point N. A source terminal of the first V-phase middle elementis connected to a source terminal of the second V-phase middle element. A drain terminal of the second V-phase middle elementis connected to the source terminal of the second switching elementand a drain terminal of the third switching element. In other words, the drain terminal of the second V-phase middle elementis connected to the V-phase coilof the motor. The second middle element portionmay be referred to as a V-phase middle element.

115 115 115 115 1 115 115 115 112 112 115 123 12 115 a b a p a b b a b b The third middle element portionincludes a first W-phase middle elementand a second W-phase middle elementas the two switching elements. A drain terminal of the first W-phase middle elementis connected to the neutral point N. A source terminal of the first W-phase middle elementis connected to a source terminal of the second W-phase middle element. A drain terminal of the second W-phase middle elementis connected to a source terminal of the fifth switching elementand a drain terminal of the sixth switching element. In other words, the drain terminal of the second W-phase middle elementis connected to the W-phase coilof the motor. The third middle element portionmay be referred to as a W-phase middle element.

113 114 115 The first middle element portion, the second middle element portion, and the third middle element portionin the present embodiment are examples of a "middle element" according to the present disclosure.

13 11 12 13 12 12 110 110 111 111 112 112 113 113 114 114 115 115 13 11 11 2 FIG. 2 FIG. a b a b a b a b a b a b The ECUcontrols the inverterin accordance with a driving state of the motor. In the example, the ECUis connected to a gate terminal of each of theswitching elements shown inand switches on and off of each switching element. Theswitching elements shown inare the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, the sixth switching element, the first U-phase middle element, the second U-phase middle element, the first V-phase middle element, the second V-phase middle element, the first W-phase middle element, and the second W-phase middle element. Specifically, the ECUswitches on and off of each switching element in accordance with an operation mode of the inverter. The operation modes of the inverterinclude the following first mode, second mode, and third mode.

13 11 110 111 112 113 114 115 110 111 112 121 123 12 1 11 a a a b b b w In the first mode, the ECUcontrols the invertersuch that the upper arm element is turned on, the middle element is turned off, and the lower arm element is turned off. The upper arm element is the first switching element, the third switching element, and the fifth switching element. The middle element is the first middle element portion, the second middle element portion, and the third middle element portion. The lower arm element is the second switching element, the fourth switching element, and the sixth switching element. In this case, each of coilstoof the motoris conductive to the high-potential wiring line Hof the inverter.

13 11 110 111 112 113 114 115 110 111 112 121 123 12 1 11 a a a b b b p In the second mode, the ECUcontrols the invertersuch that the upper arm element is turned off, the middle element is turned on, and the lower arm element is turned off. The upper arm element is the first switching element, the third switching element, and the fifth switching element. The middle element is the first middle element portion, the second middle element portion, and the third middle element portion. The lower arm element is the second switching element, the fourth switching element, and the sixth switching element. In this case, each of the coilstoof the motoris conductive to the neutral point Nof the inverter.

13 11 110 111 112 113 114 115 110 111 112 121 123 12 1 11 a a a b b b w In the third mode, the ECUcontrols the invertersuch that the upper arm element is turned off, the middle element is turned off, and the lower arm element is turned on. The upper arm element is the first switching element, the third switching element, and the fifth switching element. The middle element is the first middle element portion, the second middle element portion, and the third middle element portion. The lower arm element is the second switching element, the fourth switching element, and the sixth switching element. In this case, each of the coilstoof the motoris conductive to the low-potential wiring line Lof the inverter.

13 11 11 12 As described above, the ECUswitches the operation mode of the inverter, so that three-phase alternating current power can be supplied from the inverterto the motor.

11 118 119 118 1 116 2 110 1 118 1 118 1 118 1 118 u u a w w w w 2 FIG. 2 FIG. In addition to the above-described components, the inverterin the present embodiment includes a first switchand a second switch. The first switchis disposed between the connection position (Pin) of the first capacitorand the connection position (Pin) of the first switching element(drain terminal) in the high-potential wiring line H. The first switchis a switch that switches conduction and interruption of the high-potential wiring line H, and is an example of a "first switching element" according to the present disclosure. In the example, the first switchmay be a single-pole single-throw switch. In the following description, the high-potential wiring line His conductive in a case where the first switchis turned on, and the high-potential wiring line His interrupted in a case where the first switchis turned off.

119 1 117 2 110 1 119 1 119 118 1 119 1 119 l l b w w w w 2 FIG. 2 FIG. The second switchis disposed between the connection position (Pin) of the second capacitorand the connection position (Pin) of the second switching element(source terminal) in the low-potential wiring line L. The second switchis a switch that switches conduction and interruption of the low-potential wiring line L, and is an example of a "second switching element" according to the present disclosure. In the example, the second switchmay be a single-pole single-throw switch similar to the first switch. In the following description, the low-potential wiring line Lis conductive in a case where the second switchis turned on, and the low-potential wiring line Lis interrupted in a case where the second switchis turned off.

118 119 13 118 119 The first switchand the second switchare controlled by the ECU. The control of the first switchand the second switchwill be described later.

3 FIG. 1 1 11 20 13 11 20 13 is a block diagram schematically showing an example of a hardware configuration of the inverter system. The inverter systemin the present embodiment includes the inverter, a current sensor, and the ECU. The inverter, the current sensor, and the ECUare connected to each other by an in-vehicle network. The in-vehicle network may be a network based on a standard such as controller area network (CAN), local interconnect network (LIN), or FlexRay.

11 1100 113 114 115 118 119 1100 110 110 111 111 112 112 1100 110 110 111 111 112 112 113 113 113 114 114 114 115 115 115 1100 113 114 115 a b a b a b a b a b a b a b a b a b The inverterincludes the switching element, the first middle element portion, the second middle element portion, the third middle element portion, the first switch, and the second switch. The switching elementis the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element. The switching elementis the first switching element, the second switching element, the third switching element, the fourth switching element, the fifth switching element, and the sixth switching element. The first middle element portionis the first U-phase middle elementand the second U-phase middle element. The second middle element portionis the first V-phase middle elementand the second V-phase middle element. The third middle element portionis the first W-phase middle elementand the second W-phase middle element. The functions of the switching element, the first middle element portion, the second middle element portion, and the third middle element portionare as described above.

20 1100 20 210 110 210 110 20 211 111 211 111 20 212 112 212 112 a a b b a a b b a a b b The current sensordetects a current value flowing through each of the six switching elements included in the switching element. Specifically, the current sensoris configured to include a first current sensorthat detects a current value flowing through the first switching elementand a second current sensorthat detects a current value flowing through the second switching element. The current sensoris configured to include a third current sensorthat detects a current value flowing through the third switching elementand a fourth current sensorthat detects a current value flowing through the fourth switching element. The current sensoris configured to include a fifth current sensorthat detects a current value flowing through the fifth switching elementand a sixth current sensorthat detects a current value flowing through the sixth switching element.

13 13 13 The ECUcan be configured as a computer having a processor (CPU, GPU, or the like), a main memory (RAM, ROM, or the like), and an auxiliary memory (EPROM, hard disk drive, removable media, or the like). Various programs, various tables, an operating system (OS), and the like are stored in the auxiliary memory, and each function of the ECUis realized by the processor executing the program stored therein, as will be described later. However, some or all of the functions may be realized as a hardware module by, for example, a hardware circuit such as an ASIC or an FPGA. The ECUin the present embodiment is an example of a "control device" according to the present disclosure.

13 130 131 130 13 130 130 130 The ECUin the present embodiment includes a controllerand a storage unit. The controlleris an operation unit that realizes various functions of the ECUby executing a predetermined program stored in the auxiliary memory. The controllercan be realized by, for example, a hardware processor such as a CPU. In addition, the controllermay be configured to include a RAM, a ROM, a cache memory, and the like. The function realized by the controllerwill be described later.

131 131 130 The storage unitis a unit that stores various types of information, and is configured by a storage medium such as a RAM, a magnetic disk, and a flash memory. The storage unitstores a predetermined program executed by the controller, data used by the program, and the like.

11 13 1 1 12 10 10 h h Various sensors for acquiring sensor data used for controlling the inverterare also connected to the ECU. The sensors may include, for example, a sensor that detects an operation amount of an accelerator pedal, a sensor that detects a traveling speed of the vehicle V, and a sensor that detects an acceleration of the vehicle V. The sensors may include, for example, a sensor that detects an operation amount of a brake pedal, a sensor that detects a shift position, and a sensor that detects a rotation speed of the motor. The sensors may include, for example, a sensor that detects a remaining power of the batteryand a sensor that detects a temperature of the battery.

1 130 13 11 11 In the inverter systemconfigured as described above, the controllerof the ECUswitches the operation mode of the inverterin accordance with the sensor data as described above. The operation modes of the inverterinclude the first mode, the second mode, and the third mode described above.

1 130 13 118 118 110 111 112 a a a In addition, in the inverter systemin the present embodiment, the controllerof the ECUcontrols the first switchto be turned on in a case where the upper arm element is normal, and controls the first switchto be turned off in a case where the upper arm element fails. The upper arm element is the first switching element, the third switching element, and the fifth switching element. The failure of the upper arm element referred herein is a failure (short-circuit failure) in which a current flows through the upper arm element even though the upper arm element is controlled to be turned off.

210 211 212 11 11 210 211 212 130 a a a a a a The short-circuit failure of the upper arm element is determined in accordance with the current value detected by each of the first current sensor, the third current sensor, and the fifth current sensorin a case where the inverteroperates in the second mode or the third mode (in a case where the upper arm element is controlled to be turned off). In the example, in a case where the inverteroperates in the second mode or the third mode, and at least one of the first current sensor, the third current sensor, or the fifth current sensordetects a current value larger than a predetermined threshold value (for example, 0 amperes), the controllermay determine that at least one of the three upper arm elements is short-circuited.

130 118 11 4 FIG. In a case where the short-circuit failure of at least one of the three upper arm elements is detected as described above, the controllerswitches the first switchfrom on to off as shown in. As a result, even in a case where the middle element is turned on in a state where the upper arm element is short-circuited, it is possible to prevent the middle element from being short-circuited. As a result, the invertercan operate in the second mode and the third mode.

1 130 13 119 119 110 111 112 b b b In addition, in the inverter systemin the present embodiment, the controllerof the ECUcontrols the second switchto be turned on in a case where the lower arm element is normal, and controls the second switchto be turned off in a case where the lower arm element fails. The lower arm element is the second switching element, the fourth switching element, and the sixth switching element. The failure of the lower arm element referred herein may be a short-circuit failure.

210 211 212 11 11 210 211 212 130 a a a a a a The short-circuit failure of the lower arm element is determined in accordance with the current value detected by each of the first current sensor, the third current sensor, and the fifth current sensorin a case where the inverteroperates in the first mode or the second mode (in a case where the upper arm element is controlled to be turned off). In the example, in a case where the inverteroperates in the second mode or the third mode, and at least one of the first current sensor, the third current sensor, or the fifth current sensordetects a current value larger than a predetermined threshold value (for example, 0 amperes), the controllermay determine that at least one of the three upper arm elements is short-circuited.

130 119 11 5 FIG. In a case where the short-circuit failure of at least one of the three lower arm elements is detected as described above, the controllerswitches the second switchfrom on to off as shown in. As a result, even in a case where the middle element is turned on in a state in which the lower arm element is short-circuited, it is possible to prevent the middle element from being short-circuited. As a result, the invertercan operate in the first mode and the second mode.

13 13 1 11 6 FIG. 6 FIG. h Here, an operation of the ECUin the present embodiment will be described with reference to.is a flowchart showing an example of a processing routine that is repeatedly executed by the ECUin a predetermined period (for example, about several hundred microseconds to several tens of milliseconds) during the start of the vehicle V(during the operation of the inverter).

6 FIG. 130 13 11 101 11 101 110 111 112 130 102 103 a a a In the processing routine of, first, the controllerof the ECUdetermines whether the inverteroperates in the second mode or the third mode (S). In a case where the inverteroperates in the second mode or the third mode (affirmative determination in S), the upper arm element is controlled to be in an off state, so that it is possible to detect the short-circuit failure of the upper arm element. The upper arm element is the first switching element, the third switching element, and the fifth switching element. Therefore, the controllerexecutes the determination processing of whether the upper arm element is short-circuited in Sto S.

102 130 110 111 112 210 211 212 a a a a a a In S, the controlleracquires the current value (detection value) flowing through each of the first switching element, the third switching element, and the fifth switching elementthrough the first current sensor, the third current sensor, and the fifth current sensor.

103 130 210 211 212 210 211 212 103 110 111 112 210 211 212 103 110 111 112 a a a a a a a a a a a a a a a In S, the controllerdetermines whether there is a detection value larger than a predetermined threshold value in the detection values of the first current sensor, the third current sensor, and the fifth current sensor. In a case where there is a detection value larger than the predetermined threshold value in the detection values of the first current sensor, the third current sensor, and the fifth current sensor(affirmative determination in S), among the three upper arm elements, the upper arm element in which the detection value larger than the predetermined threshold value is detected can be regarded as being short-circuited. The three upper arm elements are the first switching element, the third switching element, and the fifth switching element. On the other hand, in a case where there is no detection value larger than the predetermined threshold value in the detection values of the first current sensor, the third current sensor, and the fifth current sensor(negative determination in S), it can be regarded that none of the three upper arm elements is short-circuited. The three upper arm elements are the first switching element, the third switching element, and the fifth switching element.

103 130 104 118 103 130 105 118 104 105 6 FIG. In a case where the affirmative determination is made in S, the controllerproceeds to processing of Sand controls the first switchto be turned off. On the other hand, in a case where the negative determination is made in S, the controllerproceeds to processing of Sand controls the first switchto be turned on. In a case where the processing of Sor Sis executed and ended, the ECU 13 ends the execution of the processing routine of.

101 11 101 110 111 112 130 106 107 b b b In addition, in a case where it is determined in Sthat the inverteroperates in the first mode (negative determination in S), the lower arm element is controlled to be in an off state, so that it is possible to detect the short-circuit failure of the lower arm element. The lower arm element is the second switching element, the fourth switching element, and the sixth switching element. Therefore, the controllerexecutes the determination processing of whether the lower arm element is short-circuited in Sto S.

106 130 110 111 112 210 211 212 b b b b b b In S, the controlleracquires the current value (detection value) flowing through each of the second switching element, the fourth switching element, and the sixth switching elementthrough the second current sensor, the fourth current sensor, and the sixth current sensor.

107 130 210 211 212 210 211 212 107 110 111 112 210 211 212 107 110 111 112 b b b b b b b b b b b b b b b In S, the controllerdetermines whether there is a detection value larger than a predetermined threshold value in the detection values of the second current sensor, the fourth current sensor, and the sixth current sensor. In a case where there is a detection value larger than the predetermined threshold value in the detection values of the second current sensor, the fourth current sensor, and the sixth current sensor(affirmative determination in S), among the three lower arm elements, the lower arm element in which the detection value larger than the predetermined threshold value is detected can be regarded as being short-circuited. The three lower arm elements are the second switching element, the fourth switching element, and the sixth switching element. On the other hand, in a case where there is no detection value larger than the predetermined threshold value in the detection values of the second current sensor, the fourth current sensor, and the sixth current sensor(negative determination in S), it can be regarded that none of the three lower arm elements is short-circuited. The three lower arm elements are the second switching element, the fourth switching element, and the sixth switching element.

107 130 108 119 107 130 109 119 108 109 13 6 FIG. In a case where the affirmative determination is made in S, the controllerproceeds to processing of Sand controls the second switchto be turned off. On the other hand, in a case where the negative determination is made in S, the controllerproceeds to processing of Sand controls the second switchto be turned on. In a case where the processing of Sor Sis executed and ended, the ECUends the execution of the processing routine of.

1 11 118 11 11 110 111 112 1 116 2 110 1 113 114 115 11 11 a a a u u a w 2 FIG. 2 FIG. In the inverter systemaccording to the present embodiment, in a case where at least one of the three upper arm elements of the inverteris short-circuited, the first switchof the inverteris turned off. The three upper arm elements of the inverterare the first switching element, the third switching element, and the fifth switching element. As a result, a portion between the connection position (Pin) of the first capacitorand the connection position (Pin) of the first switching element(drain terminal) in the high-potential wiring line His interrupted. As a result, even in a case where the middle element (first middle element portion, second middle element portion, and third middle element portion) of the inverteris turned on, the middle element is not short-circuited. Therefore, in a case where at least one of the three upper arm elements is short-circuited, the invertercan operate in the second mode and the third mode.

1 11 119 11 11 110 111 112 1 117 2 110 1 113 114 115 11 11 b b b l l b w 2 FIG. 2 FIG. In addition, in the inverter systemaccording to the present embodiment, in a case where at least one of the three lower arm elements of the inverteris short-circuited, the second switchof the inverteris turned off. The three lower arm elements of the inverterare the second switching element, the fourth switching element, and the sixth switching element. As a result, a portion between the connection position (Pin) of the second capacitorand the connection position (Pin) of the second switching element(source terminal) in the low-potential wiring line Lis interrupted. As a result, even in a case where the middle element (first middle element portion, second middle element portion, and third middle element portion) of the inverteris turned on, the middle element is not short-circuited. Therefore, in a case where at least one of the three lower arm elements is short-circuited, the invertercan operate in the first mode and the second mode.

1 1 11 h Therefore, with the inverter systemaccording to the present embodiment, it is possible to improve limp home performance of the vehicle Vin a case where the upper arm element or the lower arm element of the inverteris short-circuited.

11 118 119 11 118 119 In the embodiment described above, an example has been described in which the inverterincludes both the first switchand the second switch, but the invertermay include only one of the first switchor the second switch.